Question

I was trying to setup a unit test for a private inner class, but had very little success:

namespace Stats.Model
{
  public class DailyStat
  {
    private class DailyStatKey // The one to test
    {
      private DateTime date;
      public DateTime Date 
      { 
        get { return date; }
        set { date = value.Date; }
      }

      public StatType Type { get; set; }

      public override int GetHashCode()
      {
        return Date.Year * 1000000 +
               Date.Month * 10000 +
               Date.Day * 100 +
               (int)Type;
      }

      public override bool Equals(object obj)
      {
        DailyStatKey otherKey = obj as DailyStatKey;
        if (otherKey == null)
          return false;
        return (this.Date == otherKey.Date && this.StatType == otherKey.StatType);
      }
    }
  }
}

I tried this code:

PrivateType statKeyType = new PrivateType("Stats.Model", "Stats.Model.DailyStat.DailyStatKey");

as well as

PrivateType statKeyType = new PrivateType("Stats.Model", "DailyStat.DailyStatKey");

To no avail.

The assembly’s name is “Stats.Model”, and to me the type name looks correct too, but I just get an exception: “System.TypeLoadException: Could not load type”

So what am I doing wrong ?

PrivateType, to the best of my knowledge, is reflection based, and I’d guess it’s pretty much intended for this scenario, as you cannot have a private class directly beneath a namespace.

EDIT:

Added full implementation of DailyStatKey. What I want to test is the uniqueness of my GetHashCode method. As you can see I try to fit a date + type into a single int.

Answer 1

Found a solution myself:

var parentType = typeof(DailyStat);
var keyType = parentType.GetNestedType("DailyKeyStat", BindingFlags.NonPublic); 
//edited to use GetNestedType instead of just NestedType

var privateKeyInstance = new PrivateObject(Activator.CreateInstance(keyType, true));

privateKeyInstance.SetProperty("Date", DateTime.Now);
privateKeyInstance.SetProperty("Type", StatType.Foo);

var hashCode = (int)privateKeyInstance.Invoke("GetHashCode", null);